复 杂 环 境 下 风 冷 柴 油 机 工 作 及 冷 却 性 能 研 究

Taking a V-type air-cooled diesel engine as the research object，the working performance and heat dissipation ability of the engine were studied under different altitude and temperature environments，in order to improve its thermal efficiency. The power cabin model was discretized to build the cooling system model，and the cooling system model was coupled with the diesel engine working model to simulate the process of engine cooling and heat dissipation. Results show that under the conditions of 2 000 r/min external characteristic of the diesel engine，the increase of altitude and temperature of the external environment causes the working curve of combustion in the diesel engine cylinders to shift backward. For every 1 000 m increase in altitude，the peak point of heat release moves back by 2°，and the gas temperature in the cylinder increases. At a certain speed，the air mass flow of the fan decreases with the increase of altitude and temperature，meanwhile the cooling capacity of the diesel engine decreases，and the average temperature of cylinder head fire surface increases. The thermal efficiency of the diesel engine decreases with the increase of altitude and temperature. At high altitudes and high temperatures，the increase of fan speed can improve the thermal efficiency of the diesel engine. With the increase of the fan speed，the thermal efficiency of the diesel engine changes from 29. 7% to 35. 7% at the altitude of 4 000 m and the temperature of 20 ℃.